Mine has gone exactly the same!!! It's about 4ft high now, half the leaves have fallen off and the rest are all hanging down like yours!! Gonna try it in a cooler spot in the conservatory, but I think mines heading for the bin
This is what I found on Google. I looked at several sites but this sums it up... "You can tell if your rubber plant needs more light if it becomes leggy, its leaves lose their luster, and lower leaves fall off."